1. Field
The described technology relates generally to a rechargeable battery having an electrode assembly and a current collecting plate connected to each other through a welding structure.
2. Description of the Related Technology
A rechargeable battery typically includes an electrode assembly, a case for housing the electrode assembly, a cap plate for opening and closing an opening of the case, a current collecting plate connected to an uncoated region of the electrode assembly, and an electrode terminal electrically connected to the current collecting plate and protruded to the outside of the cap plate. The electrode assembly typically includes a separator and positive and negative electrodes disposed on both sides of the separator, which are spirally wounded in a jelly-roll shape.
The uncoated region and the current collecting plate are typically mechanically and electrically connected to each other through welding. For example, an uncoated region is typically laid over a current collecting plate, and the uncoated region is typically welded to the current collecting plate by applying ultrasonic wave vibration in an ultrasonic welding method. If a width of the uncoated region is narrow, it is difficult to join the uncoated regions between a horn and an anvil of an ultrasonic welder.
In a laser welding method, a protrusion member of a current collecting plate is typically stood vertically on the uncoated region, and the protrusion member is typically welded to the uncoated region by radiating a laser beam. However, it is difficult to ensure that the uncoated region is uniformly adhered to the current collecting plate.
In laser welding, a slit is formed at the current collecting plate, and the uncoated region is inserted into the slit. Even in this case, it is also difficult to join the uncoated regions when a width of the uncoated region is narrow, and the separator may be damaged because the laser beam penetrates through the electrode assembly after passing through the uncoated region.
In order to improve welding performance, a contact area of the current collecting plate and the uncoated region can be widened by bending a predetermined part of the uncoated region. In this case, it is difficult to bend the uncoated region with a constant width. Further, it is difficult to spirally wind the bended positive electrode or the bended negative electrode.
The information disclosed in this section is only for enhancement of understanding of the background of the described technology and therefore may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.